Saturday 25 August 2012 11.25 EDT
First published on Saturday 25 August 2012 11.25 EDT

At night, when Mo Farah shuts his eyes and falls asleep, the roar from the Olympic Stadium still seems to run around his mind. The noise when Farah crossed the line in the 5,000m final was so great that it actually spoiled the automatic photo of the finish, because Omega's camera was vibrating in the tumult.

Not that Farah will be sleeping much at the moment anyway; even the echo of the 80,000 will not drown out the sound of his newborn twin girls, who were delivered in London on Friday. Farah and his wife have not named them yet, but once they have he says he is going to have their names engraved into his two Olympic gold medals – "one on each", he explains with a grin. "The one who was born first gets the 10km, and the one born second gets the 5km."

After a dizzying three weeks, Farah is still in a daze. He says his main emotion now is relief. "Because my wife has been holding on so long, and it is great that she held on this long and didn't give birth on the track. She timed her kick well," he said. "Not," he adds with a chuckle, "like me in Daegu." He was recalling the 10,000m race he lost at the world championships in 2011, when he was overtaken in the final 100m. He can afford to laugh about his defeats now.

Twins, Farah says, seem to "run in the family", before speaking for the first time about his own twin brother, Hassan, who still lives in Somalia. The two were separated when they were eight, when Farah's parents made the decision to send him to join his father in Britain. That story has also only emerged since the Olympics. Farah says it was "crazy" to open the papers and see his own family splashed across the centre pages, but, he adds: "I guess that's what comes along with it."

Farah explains that he has never told the world about his twin, who was also a gifted runner, because he has never felt the time was right. "It is a true story," Farah says. "I just wanted to come out and say it in my own words later in my career, I didn't want it to overshadow my Olympics, which is something I had trained so hard for all my career. I wanted to save it and say it in my own words, but unfortunately it came out through someone else."

Farah, always so unassuming and open in his manner, has certainly got a little more savvy about how to play these games. He does not want to say too much about his own twin brother, or the birth of his girls, because, he says, "we will save it for my book and talk about it in more detail there". It, he assures his audience, "is going to come out at some point soon". His agent Ricky Simms, who also handles Usain Bolt, is sitting at the back of the room, and, you imagine, nodding his head in approval.

In the meantime, Farah will enjoy his well-deserved lap of honour, which started the moment he crossed the line in the 5,000m final and will continue until the end of the season. "When I won that 5km everything went really crazy," he says, shaking his head. "There are no words to describe it." The only comparison he could reach for, he said, was "when you are a kid at a football match, and a goal goes in and you get excited and it gets louder and louder and everybody is celebrating." It felt like that, he says, "but twice as loud".

"I have never experienced anything like that," Farah continues, "and I don't think I will ever experience something like that again." Not just him, the other runners in the two finals were similarly amazed. Farah says they have told him: "We couldn't believe how loud it was." The USA's Bernard Lagat, who has competed at four Olympic Games, told Farah: "We knew where you were, I knew when you were coming close to the front, I knew when you were following, because it was getting louder and louder and louder, I can't believe how many people were shouting out your name and giving you that support."

Farah is back on the track on Sunday, running two miles at the Aviva Grand Prix in Birmingham. It is an unusual distance, put on the programme specifically so that Farah can try to beat Steve Ovett's British record of 8min 13.51sec, set at Crystal Palace back in 1978. "Hopefully I will put on a good show here for all the people who couldn't watch me at the Olympics," Farah says. "It is going to be very exciting competing in England again." He does not have much competition – it should be more of a procession than a race.